Method and apparatus for removing waste from box blank sheets



2,757,,5 METHOD AND APPARATUS FOR REMOVING WASTE FROM BOX BLANK SHEETSFiled Nov. 5, 1950 F. A. WENZEL.

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Gttornegs United States Patent Frederick A. Wenzel, Milwaukee, Wis.,assignor to Cornell Paperboard Products Co., a corporation of WisconsinApplication November 3, 1950, SerialNo. 193,891

4 Claims. (CI. 93-36) This invention relates to a method of removingwaste from box blank sheets and a waste knock-out attachment for boxblank machines.

In machines for the die cutting of box blanks from cardboard sheets, thedies are usually made to cut a number of blanks from a single sheet.None of the cardboard material of the sheet is ordinarily severedcompletely, and after the sheets have been deliverd and stacked, anoperator using a manual or air-powered chisel cuts away the waste fromaround the edges of the sheet and from between the individual blanks asdefined by the die cut lines which nearly penetrate the sheet.

The present invention deals with the removal of the small areas of thesheet lying between the blanks in the interior of the sheet, these areasbeing frequently so small and inaccessible as to otter considerableproblems where their removal is dependent upon the use of a chisel.Numerous attempts have been made to eliminate such waste mechanicallyprior to the delivery of the sheet from the die cutting machine, butthese have either resulted in damage to the blanks, or have resulted inbreaking the blanks out of the sheet, thus increasing the difiiculty ofhandling the blanks thereafter. The present invention uses an air jetoperating in timed synchronism with the delivery of each blank to blowout the waste pieces from the interior of the sheet without requiringany mechanical tool to contact the sheet, and without injury to theblank, and without separation of any individual blank from the sheet asa whole.

The invention is further concerned with the manner in which the air jetWaste eliminating nozzles of my invention are so mounted and operated asto be of universal utility regardless of the sizes and shapes of the boxblanks. Not only are the nozzles adjustable from side to side across thepath of travel of the sheets delivered by the die cutting machine, andalso adjustable vertically respect ing the sheets, but their timing issubject to adjustable control so that the air blast may be set to occurat any desired point or points in the course of sheet travel.

In the drawings:

Fig. 1 is a fragmentary side elevational view of a box Fig. 5 is a viewof the cam partially in rear elevation 2,757,585 Patented Aug. 7, 1956has been removed in accordance with the present invention.

Fig. 8 is a diagrammatic plan view of an arrangement for operating theair blast control valves at individually timed intervals.

The machine for die cutting the sheets to form box blanks therefromconstitutes no part of the present invention, and portions of themachine are illustrated merely to show the application of the wasteeliminating means presently to be disclosed.

From a stack of sheets at 10, individual sheets of cardboard or the likeare successively delivered by conveyor 11 onto the matrix roll 12, aboutwhich the sheets travel to be cut in predetermined patterns by the die13. This die reciprocates beneath roll 12 to co-act. therewith and todivide the individual sheets 15 in any predetermined path of box blanksas, for example, those shown at 16 in Figs. 6 and 7.

The various flaps and tabs of the box blanks are desirably so designedas to leave a minimum of scrap between them. However, there are in thesheets shown in Fig. 6, small rectangles 17, 18, which are not used inthe blanks and constitute waste. Since it is desired that the varioussheets may be continued to be handled as such, even after the blankshave been partially severed, the waste cardboard at 17, 18 should beremoved to leave the openings and shown in Fig. 7. In such a stack ofsheets as that shown at 150 in Fig. 7, it is a matter of consider ableexpense and difiiculty to eliminate the small pieces of waste. I havesucceeded in doing this on the die cutting machine.

As the die cut sheet 15 leaves the matrix roll 12, it is engaged betweenthe upper and lower belts of conveyor 19 which deliver the sheet ontothe top of a stack 150. The truing device 20 operated by link 21 fromhell crank 22 is used to register each successive sheet at the top ofstack 150. The bell crank 22 is operated by the link 23 from the crankarm 24 on shaft 25.

This shaft, which makes one rotation in the course of the delivery ofeach sheet, is a convenient one upon which to mount the cam disk 26(Figs. 4 and 5) for the purpose of the present invention. The cam diskhas about its periphery a series of holes 27 to receive the screws 28which adjustably attach to the disk the radially projecting cams 30. Anydesired number of cams may be used. Since the particular sheet 15 shownin Figs. 6 and 7 has but three of the small rectangular pieces of waste17 in any given line in the direction of sheet travel, it is onlynecessary, for the purposes of this sheet, to employ three of the cams30.

Attached to a portion 31 of the frame of the machine in proximity toshaft 25 and cam disk 26, is a bracket 32 which adjustably supports nearits upper end a switch 33 having a switch actuator 34. Near the lowerend of the bracket is a block 35 upon which is mounted a motiontransmitting spring 36 having its intermediate portion in the path ofmovement of the successive earns 30 as they rotate with disk 26 on shaft25. Thus, in each rotation of shaft 25, the spring 36 will engage theswitch actuator 34 to close the switch circuit as many times as thereare cams 30 upon disk 36 (three in each instance). The electricalconnections 38 controlled by switch 33 are led through suitable conduits39, 40 to the top of the machine where the wires are operativelyconnected for the actuation of solenoid valves 41 controlling thedelivery of air through branch pipes 42 from the air supply means 43.

The air supply means 43 may conveniently be carried by brackets 44, 45from the sides of the machine as best shown in Fig. 3, and it may beused to carry a bar 46 upon which the clamps 47 are adjustable laterallyof the machine, being anchored in any desired adjustment along the barby their respective set screws 48 (Figs. 2 and 3).

Projecting forwardly beneath the pipe 43 from each of the clamps 47 is arod 49 for the adjustable support of the air jet nozzle 50. Each nozzleis connected by a flexible hose 51 with one of the branch pipes 42controlled by a solenoid valve. Thus, each time one of the earns 30 onshaft 23 closes the switch 33, the solenoid valves will admit air underpressure to the respective nozzles, thus instantaneously creating ablast downwardly in the direction of the sheet passing beneath thenozzles. By adjustment of the cams 30, it is possible to time this blastto occur in accurate synchronism with the passage beneath the ringnozzles of the small pieces of waste 17 which are to be removed. Thelocation of the individual nozzles may also be adjusted both laterallyand longitudinally so that the nozzles will accurately register with thewaste at the time the blast occurs. The air may be under any desiredpressure suflicient to make the blast eiiective. I

have found that in actual practice, air at a pressure of I 80 pounds persquare inch is adequate to blow out the waste pieces .17 as shown inFig. 3, thereby leaving open the holes 170 without otherwise disruptingthe sheet 15.

A pan shown at 53 in Fig. 1 is located directly beneath the conveyor 19to receive the Waste pieces 17 and 18. The pan is disposed at an angleas shown, to guide the waste pieces for collection.

If desired, the air blast nozzles may be selectively operated in anysequence by providing each solenoid valve with an individual controlswitch 33 and operating each switch with a separate cam on shaft 25 asshown diagrammatically in Fig. 8.

Since, in the particular sheets herein disclosed, it is desired not toseparate the individual blanks, I make no eifort, in the presentlydisclosed device, to remove the waste stock around the edges of thesheets as shown at 52 in Figs. 6 and 7. This stock, all of which isreadily accessible, may readily be removed by hand in the conventionalway. The hand labor required for removing the stock at the outer edge ofthe sheet is less than that which would be required to handle the sheetsif such waste were removed. However, by removing in the machine thewaste stock from the intermediate or central areas of each successivesheet, I have more than half ofthe labor heretofore required in themaking of box blanks.

While my improved method will be apparent from the foregoing disclosure,it may be summarized as comprising the following steps:

17 The die cutting of a sheet for the partial severance within the edgesof the sheet of box blanks and intervening waste areas.

2. Directing intermittently operable air blasts at the waste areas ofthe sheet to complete the severance of such areas from the sheet and todislodge the severedwaste and discharge it from the sheet.

3. The alignment of successive sheets with other sheets using theunimpaired edges of the sheets, and

4. The severance of waste, if any, from the edges of stacked sheets.

More. generically, the. invention consists in the partial severance by adie cutting operation of waste areasv from the. center of the sheet, andthe dislodgement and removal of the waste by directing an air blast atthe waste in the course of sheet delivery from the die cuttingoperation.

I claim:

1. A method of cutting a plurality of box blanks, from a sheet of boardand removing internal waste from between the blanks, which methodcomprises the steps of die cutting the sheet upon the outlines of thedesired box blanks Within the boundaries of the sheet to define theindividual blanks and internal waste by die cut lines which at leastnearly penetrate the sheet on said outlines for at least partialseverance of the blanks and internal waste pieces spaced within thesheet, completely dislodging internal waste pieces solely byintermittently directing pneumatic blasts substantially only againstsuch internal waste pieces while effecting relative movement between thesheet. and said blasts, and substantially cutting off the blasts betweeninternal waste pieces whereby the margins of the sheet are left intactwith the box blanks remaining in assembly therein.

2. The method recited in claim 1 in which the sheet is advanced pastsuccessive pneumatic blasts in the direction in which waste pieces arespaced in the sheet, said blasts being intermittently timed insynchronism with sheet advance.

3. An attachment for a machine which cuts box blanks and interveningwaste from a sheet of paper board by die cutting at least nearly throughthe sheet on the outline of the box blank and waste, such attachmentcomprising means for advancing successive sheets unitarily containingsuch box blanks and waste, and means for completely dislodging all wastefrom the sheet without displacing the sheet margins 01' the, box blankstherein, said last mentioned means comprising solely a pneumatic nozzledirected toward the path of sheet advance in alignment with the wastetherein, high pressure pneumatic connections for said nozzle, and valvemeans controlling said connections and provided with means for actuatingsaid valve means in synchronism with sheet advance upon registry of eachpiece of waste with the nozzle to blast the waste from the sheet, eachsuccessive blast from the nozzle being directed substantially onlyagainst a piece of waste independently of the rest of the sheet to leavethe box blanks and the margins of the sheet. intact while completelyremoving the internal waste.

4. The device of claim 3 in further combination with sheet. aligningmeans acting uponv the. intact margins of successive sheets from whichinternal waste pieces have been wholly removed by said blast for theaccurate stacking of successive sheets.

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